Music therapy is the scientific application of music or sound for healing, relaxation, fighting depression, and the like, in patients such as the physically and mentally ill, the mentally retarded, and aged. The fact that music affects persons in various ways has long been known, and numerous methods of applying particular types of music or sounds in certain ways to achieve particular results have been disclosed in the art. Many of these methods aim to alter physiological properties such as muscle tension, and rhythms such as brain wave frequency, heart rate, respiration rate, or circadian rhythms, e.g., body temperature variation, hormone level, blood pressure, blood sugar, and concentrations of essential biochemicals in the nervous system.
The traditional method of presenting music to a patient for this purpose comprises choosing a suitable type of music, such as a soothing classical or romantic piece if a relaxation of muscle tension is desired, and presenting it unchanged to the patient. With the development of new technologies such as realistic synthesized sound, computer technology, and convenient and non-obtrusive patient observatory mechanisms, however, new methods of provoking physiological responses to music are possible.
A technique that was developed as a departure from traditional methods of psychological therapy, was the "iso-moodic" principle, which matches musical stimuli to a patient's existing mood and subsequently changes the stimuli in the direction in which the patient's mood is to be influenced. This technique has been found to be applicable to physiological changes as well. Altshuler, A Psychiatrist's Experience with Music as a Therapeutic Agent, in Music and Medicine, eds. Schullian et al., Book for Libraries Press (1948); Pignatiello et al., A Psychophysiological Comparison of the Velton and Musical Mood Induction Techniques, 26 J. of Music Therapy 140 (1989); Rider, Entrainment Mechanisms are Involved in Pain Reduction, Muscle Relaxation, and Music-Mediated Imagery, 22 J. of Music Therapy 183 (1985); Rider et al., The Effect of Music, Imagery, and Relaxation on Adrenal Corticosteroids and the Re-Entrainment of Circadian Rhythms, 22 J. of Music Therapy 46 (1985).
An example of the iso-moodic principle affecting physiology is documented by Rider, supra, who described a presentation of iso-moodic music to spinal cord injury patients for reduction of muscle tension or electromyograph activity (EMG). The music shifted in a pre-determined fashion and sequence from unpleasant to pleasant; specifically, from a rhythm of an emotionally challenging accelerating 7/8 meter to a comfortable andante 4/4 meter. Rider found that the iso-moodic music was more effective in reducing muscle tension than four other types of music which were also presented: minimalist, jazz, impressionistic, and music preferred by the patients.
Saperston found that iso-moodic music was more effective than sedative music or silence in reducing EMG activity. Saperston, Music-Based Individualized Relaxation Training (MBIRT): Sequential Stress Reduction Techniques for the Behaviorally Disturbed Mentally Retarded, 6 Music Therapy Perspectives 26 (1989). Pignatiello et al., supra, found that iso-moodic music affected systolic blood pressure.
Notwithstanding the above, no one in the prior art has used the iso principle for anything besides a general shift in mood, the physiological responses resulting primarily as a side effect of the patient's changing mood. Iso-type music has not been structured to directly affect a specific ongoing physiological response of the patient. In addition, prior art iso-moodic music stimuli have a fixed structure, sequence, and speed; they d not take into account the reaction of the patient during presentation of the stimuli, which may be neutral or contrary to expectations. Though iso-moodic music which coaxes the patient from the initial state to the desired state through traversing that same path itself has been found to be more effective than traditional music presentation techniques, it is desirable to find even more effective methods.
The concept of the Huygens phenomenon, or entrainment, has proven useful in influencing physiological responses. Entrainment is the locking into phase of previously out-of-step oscillators, such as two pendulum clocks mounted on the same bracket. An oscillator can be anything that vibrates in a regular periodic manner. "Whenever two or more oscillators in the same field are pulsing at nearly the same time, they tend to lock in so that they are pulsing at exactly the same time. The reason, simply stated, is that nature seeks the most efficient energy state, and it takes less energy to pulse in cooperation than in opposition." Leonard, The Silent Pulse, Elsevier-Dutton Publ. Co. p. 12 (1978). It is important to note that the two oscillators must be pulsing at nearly the same time in order for entrainment to occur.
Various physiological studies have dealt with entrainment, largely with regard to circadian rhythms, and have found that physiological process rhythms are entrained to each other (internal synchronization), with environmental time cues (external synchronization), or both. It has been found that the desynchronization of physiological processes which are normally entrained can have deleterious effects on physical health, mental health, task performance, and behavior both in normal patients and those with existing physical or mental disorders.
Rider and his co-workers, supra, have found that desynchronized corticosteriod and body temperature circadian rhythms can be re-entrained through a general treatment comprising music, progressive muscle relaxation, and imagery.
More specifically, other researchers have found that auditory or musical stimuli can be systematically presented as synchronizers to influence predictable changes in physiological responses through entrainment. One study found that respiration rates approximated the rates of a regularly recurring tone. Lovell et al., Physiological and Motor Responses to a Regularly Recurring Sound: A Study in Monotony, 30 J. of Experimental Psychology 435 (1942). Another demonstrated that respiratory patterns could be entrained by prerecorded rhythmic music. Haas et al., Effects of Perceived Musical Rhythm on Respiratory Pattern, 62(3) J. of Applied Physiology 1185 (1986). Another reported that heart rates were entrained through the presentation of audible clicks at a precise time in the cardiac cycle measured from each R-wave of the subjects' electrocardiograms. Bason et al., Control of the Heart Rate by External Stimuli, 238(5362) Nature 279 (1972).
Other prior art of interest includes Landstrom et al., Changes in Wakefulness During Exposure to Whole Body Vibration. 61 Electroencephalography and Clinical Neurophysiology 411 (1985), in which a regular tone of 3 Hz presented to a patient tended to shift the patient's electroencephalogram from the alpha frequency band to the theta frequency band.
In addition to the above techniques, drug and biofeedback treatments currently are used to influence therapeutic changes in physiological processes. However, some drugs have deleterious effects, and many individuals with cognitive defects, e.g., mental retardation and dementia, those persons with emotional problems, and young children cannot benefit from traditional biofeedback training.